Maybe Corypheus' attempt to jailbreak the Orb, our intrusion and the Orb flying around the room before we picked it up, caused the magic to spiral out of control and create the Breach, meaning Corypheus might have been a tad right that we did sort of "spoil it with our stumbling!"

I've always rather thought that Solas knew the explosion was coming- not that he relished it, nor even that he necessarily thought that it would happen at the Conclave. However he absolutely knew that Corypheus was more powerful than he [Solas] was after his long nap. He flat out says that he figured on Corypheus being killed by the energies unleashed when the orb was unlocked, and that he was shocked that a Tevinter had figured out "the secret of immortality" (which ties in to another crazy theory about how the Blight, the Tevinter Old Gods, the Elven Pantheon, and how they were locked away; but I digress). I've always imagined the timeline thusly:
1. Solas arranges for Corypheus to find out about and acquire the orb.
2. Solas follows Corypheus and waits for the giant explosion so he can go reclaim the orb, manifest the anchor, enter physically into the Fade, and tear down the Veil.
3. Solas is a bit put off by the fact that Corypheus' intended blood magic requires the ritual sacrifice of a being whose level of spiritual energy (namely faith) is high due to both her own level of faith and the faith that the whole of Southern Thedas has in her- however, it's not as if this chick is really a person, and neither are the people meeting with her on a mountaintop- so hey, regrettable but acceptable losses.
4. Cue Inquisitor, who effs things up not only for Corypheus, but also for Solas himself.
5. Begin events of Inquisition.